Carburetor



Nov. 7, 1950 H. s. BRQWN ETAL 252923242 CARBURETOR Filed Sept. l0, 19493 Sheets-Sheet 1 Nov.7 7, 195o H. s. BROWN ETAL 2,529,242

CARBURETOR Filed sept. 1o, 1949 s sheets-sheet 2 l l TM- g Et/ ZL Nov.7, 1950 H. s. BROWN Erm. 2,529,242

cARBUREToR Filed Sept. 10, 1949 3 Sheets-Sheet 3 Patented Nov. 7, 1950 yCARBURETOR Hugh S. Brown, Wauwatosia., and Werner E. Armstrong andJoseph V. Reichenbach', Milwaukee,

Wis., assignors to Bri tion, Milwaukee, ware ggs & Stratton Corpora-Wis., a corporation oi' Dela- Application September 10, 1949, Serial No.114,982

This invention relates to carburetors and refers particularly tocarburetors especially adapted for use on single cylinder internalcombustion engines.

One of the chief objects of this invention is to simplify and reduce thecost of such carburetors without sacrificing full economy, goodperformance and adequate engine power.

vWith 'a view toward satisfying this objective, it is another object ofthis invention to provide a carburetor in which the customary iioat feedis supplanted by a simple suction tube through which fuel is lifteddirectly from the tank to the jet in response to engine suctionmanifested at the jet.

In this connection it is another object of this invention to provide acarburetor wherein the body not only provides a fuel mixture passage butalso constitutes a load carrying member in that it has the fuel tanksuspended from the underside thereof.

Again with a view toward simplicity and low cost it is a further objectof this invention to form the body of the carburetor as a die casting sodesigned and shaped as to provide an open topped cylindrical well toreceive a barrel-like throttle valve which is held in place byinterengaging abutments so placed on the die cast body and the valvethat disengagement thereof requires rotation of the valve to a positionbef yond one of its normal limits of rotation.

Another object of this invention is to provide a simple choke for thecarburetor which lends l itself well to assembly with the die cast body.

Another object of this invention is to provide a carburetor of thecharacter described having governor actuated means for controlling theposition of the throttle valve and hence the speed of the engine and anovel manner of adjusting the spring against which the governor actswith a view toward facilitating access and manipulation of the screw bywhich this adjustment is effected.

In this connection it is another object of this invention to so disposethe adjusting screw for the tension spring that access thereto may be 4Claims. ('Cl. 123-119) had from the same side of the carburetor body atwhich the needle valve screw is adjusted, and with both adjustmentscrews positioned in the space directly above the fuel tank to beprotected from underneath by the tank.

Another object of this invention is to provide for remote control of thethrottle while at the same time retaining governor control therefor.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed, and more particularly defined by the appended claims, itbeing understood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope oftheclaims.

The accompanying drawings illustrate one complete example of thephysical embodiment of the invention constructed in accordance with thebest mode so far devised for the practical application 4of theprinciples thereof, and in which:

Figure 1 is a perspective view showing a portion of a one cylinderinternal combustion engine with the carburetor of this invention appliedthereto, the air cleaner being omitted in this view;

Figure 2 is a top plan view of the carburetor, again with the aircleaner removed, and with a part of the ange upon which the air cleanersets broken away to better illustrate the choke valve;

Figure 3 is a side view of the carburetor with parts broken away and insection;

Figure 4 is a cross sectional view taken through Figure 3 on the planeof the line 4 4;

Figure 5 is a horizontal sectional view taken through Figure 3 on theplane of the line 5 5;

Figure 6 is a side view similar to Figure 3 but illustrating the mannerin which remote control is provided for the throttle;

Figure 7 is a fragmentary side view showing a slightly modified form ofremote control; and

Figure 8 is a detail sectional view through Figure 7 on the plane of theline 8 8.

Referring now particularly to the accompanying drawings in which likenumerals indicate like parts throughout the several views, the numeral 5indicates generally the carburetor of this in vention. The body 6 of thecarburetor is an elongated hollow die casting having a longitudinallyextending bore 'I opening to one end of the body, and an attachingflange 8 at said end. The attaching fiange provides means by which thebody is securable to the cylinder 9 of an engine.

The engine, of course, may be of any desired construction with itscylinder either vertical as shown or horizontal. In any event when thecarburetor is secured in place on the cylinder the mouth of its bore iwhich provides a mixture or induction passage opens to the intake portI0 of the engine and the body 6 projects horizontally outwardly from thecylinder as a rigid load carryinsr member.

At its outer end portion the body has a downwardly projecting bracket II having a at bottom wall I2. 'This bracket serves to strengthen thebody and its flat bottom wall provides a gasket flange to which a fueltank I3 is secured with a gasket H interposed therebetween. The top andbottom walls of the tank are substantially flat and parallel, andthe topwall thereof is reinforced by a plate I5 into which the mounting screwsare threaded.

The extreme outer end portion of the tubular body has an upstandinghollow boss I6 formed thereon, the hollow interior of which defines awell communicating with the bore 1 through an air inlet opening I6 inthe bottom thereof. A flange I1 at the top of this boss provides a baseupon which a conventional air cleaner I8 is seated, the air cleanerbeing held in place in the s customary manner by a tension screw I9extending downwardly through the center thereof and anchored as at 20.Thus with the carburetor mounted on the engine cylinder in the mannerdescribed engine suction draws air into the outer end of the mixturepassage'provided by the bore 1. Engine suction also draws fuel fromthetank into the mixture passage through a jet indicated generally bythe numeral 2 I.

The jet 2| is located in a socket 22 extending axially into a boss 23formed on the side of the body. A plurality of orifices 24 providerestricted communication between the jet socket and the mixture passage,and a needle valve seat 25 threaded into the socket coacts with a needlevalve 26 to meter the flow of fuel into the mixture f passage. Enginesuction manifested at the jet draws fuel into the socket 22 outwardly ofthe needle valve through a suction pipe 21 which extends down throughthe bottom of the bracketv and the top wall of the tank to have itslower open end terminate slightly above the bottom wall of the tank. Ascreen 28 is preferably secured over the open lower end of the suctionpipe to preclude the admission of foreign matter into the pipe, butotherwise the suction pipe is open, no check valve being needed due tothe direct lift suction action.

The manner in which the suction pipe is held in place is another exampleof the simplicity and low cost which characterizes this invention. Asshown in Figure 4, the bottom wall I2 of the bracket from which thesuction pipe depends is formed with an annular V-shaped groove-29surrounding the hole into which the suction pipe fits and the adjacentportion of the pipe is slightly reduced in diameter before beingassembled with the body. After the pipe is inserted into the body theinner peripher-al edge of the groove 29 is pressed inwardly, thuslocking the suction pipe in place.

Attention is also directed to the factvthat the head 30 of the needlevalve adjusting screw is accessible at the side of the body above thefuel tank and that the axis of the screw lies in a plane parallel withthe top Wall of the tank and substantially perpendicular to the axis ofthe mixture passage 1. The advantage of this location of the needlevalve adjusting screw will beapparent hereinafter.

Adjacent to the point at which the fuel jet valve, like the body 6, ismade as a die casting and has upper and lower cylindrical end portionsfrom/ the bottom of the valve.

mouth of the socket. The cylindrical end por-- tions of the valve arethus journaled in thesocket above and below the bore 1 while the fiatmiddle portion extendsdirectly across the bore to control flowtherethrough.- `Since the valve turns ori a vertical axis there islittle chance of its binding in the socket, and to further reduce thelikelihood of bonding, its area of contact 'with the bottom of thesocket upon which it rests is reduced to e, minimum through theprovision of a small central foot or pad 34 projecting down It is to benoted that the axis about which the throttle valve turns lies in avertical plane which is normal to the axis of the induction passage andintersects the wall thereof at a point closely adjacent to the orifices24. Hence one edge of the vane 35, which constitutes the throttle valveproper and functions in the manner of a butterfly valve, swings f' toand from a position directly adjacent to the mouths of the orifices 24.This positional relationship, which is best shown in Figure 5, providesa simple manner of securing the desired balance for the carburetor sinceby slightly shifting the location of the orifices'24 lengthwise of theinduction passage and hence with respect to the orbit of the throttlevalve, the relative effect of engine suction upon air and fuel injectionmay be varied.

It will also be seen that since the socket 22 lies to one side of theinduction passage and is at substantially the same elevation above thetop of the fuel tank as the induction passage, the height to which thefuel must be lifted is held to a minimum.

The upper cylindrical end 33 of the valve has a head 31 formedintegrally therewith, the underside of which has an annular groove 38 toreceive the neck provided by the upper portion of the boss 36. Thisinterengagement between the neck surrounding the mouth of the valvesocket and the head 31 of the valve provides a free running seal betweenthe valve and the mouth of the socket.

Since the body 6 constitutes a load carrying member it is desirable toprovide as much reinforcement therefor as possible. To this end sideribs 39, a top rib 4I! and a bottom rib 4I are formed along the lengthof the body to merge with the attaching flange. 8. The top rib 40 isinterrupted by the boss 36 which defines the top of the valve socket,and at one side of this boss the rib 4B is enlarged to provide a stop 42and at the other side thereof the rib 40 is undercut to provide anoverhanging ledge 43. This ledge 43 coacts with a segment-like flange 44integral with the head 31 of the valve to hold the Valve in the socketexcept when the valve is turned beyond one of its normal limits ofrotation.

One of these limits of rotationis defined by the engagement of a radialarm 45 projecting from the head ofthe valve with one side of the stop42. The position thus defined is the full openposition of the valve. Theother or idling position is defined by the engagement of a screw 4B withthe stop 42, the screw 46 being adjustably threaded in another arm 41extending ra'- dially from the head of the valve. A spring 63 encirclingthe screw 46 bears against the under- 5. side of its headl and thusfrictionally holds the screw in adjusted position.

As will be readily apparent the `adjustability of the screw 46 enablesthe valve to be turned far enough in a counterclockwise direction (asviewed inFigure 2) to bring the segment-like flange 44 clear of theoverhanging ledge 43. This manner of securing the valve in position isparticularly advantageous in assembly since it merely requires droppingthe valve into its socket and threading the screw 46 into properDOSition.

Another expedient designed to facilitate assembly and thus reduce thecost of the carburetor is the manner in which the choke valve indicatedgenerally by the numeral 46 is designed. The function of the choke valveis, of course, to regulate the amount of air admitted into thecarburetor mixture chamber. Hence, it is mounted directly adjacent tothe air inlet and consists merely of a slide valve 49 longitudinallyslidable in a guideway 50 formed in the top face of a bracket Iextending outwardly from the closed outer end of the body which isslotted as at 52 to accommodate the \inner end o1' the slide valve. Theslide fvalve 49 is thus movable across 'the air inlet opening I6' in the6 41 on the'valve where it i's held by the screw 46 and its holdingspring 63.

The response of the governor vane 56 to air pressure is opposed by aspring 65, the tension of which determines the speed at which the enginewill run. The manner in which this for the lever 61 and also clamps astamping 66 bottom of the hollow boss I6 to regulate the passage of airthrough the opening into the mixture passage 1 provided by the hollowinterior of the body.

The valve 49 is held in place by a friction plate 53 overlying the topof the valve and which in turn is drawn downwardly and secured againstdisplacement by a spring 54 coiled about the lower end of a rivet 55,the rivet extending down through the friction plate 53, an elongatedslot in the valve and the bracket 5I, and the spring 54being confinedbetween the lower head of the rivet and the bottom of the bracket. Anysuitable means, not shown, may be provided for sliding the valve 49 backand forth to control the amount of air entering the mixture passage.

Inasmuch as the carburetor of this invention is designed especially foruse in small portable single cylinder engines which often are calledupon to operate entirely unattended, it is de` sirable to provide anautomatic control for the throttle valve to thereby coordinate the speedof the engine with the load imposed thereon.

Such controls, of course, are not new in themselves, Patent No.1,660,079 issued tov Perry E. Mack, being an example thereof.

As in the aforesaid patent the control here employed also utilizes avane 56 mounted to be influenced by air pressure emanating from theVentilating fan blades 51 on the fly wheel 58 of the engine, this airblast being directed and guided by a shroud 59.` The blade 56 which issecured to a hinged actuator arm 60 is adapted to be moved toward theright in Figure 1 by the air blast. Such movement of' the blade and arm60 is imparted to the throttle valve through a wire link 6I to rotatethe valve toward its idling position and thus slow up the enginewhenever the engine speeds up due to a diminishing load.

Though, as will be readily appreciated, the end of the wire 6I could behooked directly to some part of the throttle valve, to simplify the diecasting thereof a stamped sheet metal attach- `ing clip 62 is providedfor this purpose. This -clip is conveniently held in place by the idleadjusting' screw 46. To this end the clip has a part 64 which overliesand embraces the arm to the side of a boss 69 which forms part of thebody bracket II. This detail is shown in Figure 5.

The stamping 66 has an arcuate part 1I bent back to form an inclined camsurface across which the free end of the lever 61 swings so that a screw12 threaded into the lever and bearing against the inclined cam 1Iincreases the tension on the spring as the screw 12 is threaded fartherinto the lever 61. The screw 12 thus constitutes the speed adjustingscrew, and to hold the same against accidental displacement fromadjustment a compression spring is interposed between its head and theouter face of ,the lever 61.

Since the head of the screw 12 faces in the same direction as the head30 of the needle valve screw and since these screws are parallel andrelatively closely adjacent to each other, adjustment of the needlevalve and-the tension of the spring 65 to determine the speed at whichthe engine will run may be simply and conveniently accomplished.

It is to be noted that whereas the throttle valve is moved in onedirection by the governor mechanism and in the other direction by the.spring 65, there are no forces acting upon the valve in a Way whichcould cause it to bind in its socket. The spring is tensioned directlybetween the governor arm 60 and the adjustable lever 61, and motion ofthe governor arm 60 produced either by the spring or the air blast istranslated into rotation of the throttle valve through the link 6 I. Thespring force is thus not carried through the throttle valve to thegovernor. If the pull o f the spring in anywise imposes a side thrustupon the valve, as is common in carburetor controls of the past, theresulting tendency to tilt the valve in its socket causes it to stick orbind and thereby render the automatic control of the engine unreliable.

This particular manner of adjustably anchoring the spring 65 also lendsitself well to remote control of the spring tension and consequently thegovernor maintained engine speed. Thus as shown in Figure 6, by removalof the screw 12 and connection of a remote control wire 14 to the lever61 it is possible to quickly and easily adjust the lever andconsequently the tension of the spring. The wire 14 slides in a flexiblesheath 15 which is anchored in a boss 16 forming part of the bracket lI.

The arrangement shown in Figure 6 provides no means for retaining thelever 61 in adjusted position and depends upon whatever means areemployed for actuating the wire 14 to perform this function; whereas thearrangement'shown in Figures '7 and 8 does provide means forfrictionally holding the parts in adjusted position. As here shown thelever 61 is replaced by a longer lever 11 and the arcuate part 1 I ofthestamping the engine cylinder.

7 instead of being bent down to form a cam is left flat to have thelever 1.1 slide thereacross as it swings about its pivot.

A spring tensioned friction clamp 18 carried by the lever 11 engages theother side of the arcuate arm 'Il' as shown in Figure 8 to frictionallyhold the lever in' any adjusted position The lever 11 is, of course,movable back and forth in any suitable manner either directly or bymeans of a remote control wire (not shown).

Attention is directed to the fact that the attaching ange 8 of thecarburetor body has four bolt holes and that the cylinder has only twotappedv holes for the reception of the cap screws 1a by which the ange 8is bolted to the cylinder. Also the bolt holes of the flange 8 areeguispaced so that either set `of its diametrically opposite holes maybe aligned with the tapped holes in Thus the carburetor body may besecured to the engine cylinder in either of two positions ninety degreesapart. 'I'his enables the carburetor'toibe upright whether its cylinder'is vertical or horizontal, so that in either position the bottoni I2 ofthe bracket and consequently the fuel tank I3 is horizontal.

' As shown the fuel tank is relatively shallow. This minimizes theheight the fuel has to be tendingupwardly from the body mdially of theends of the bore and having a cylindrical bore extending axially 'downintol it with its axis intersecting that of the longitudinal bore of thebody y the side of the body above said flange, said last lifted. It is,of course, desirable to hold this height to a minimum but in actualpractice it has been found that as long as the fuel does not have to belifted much more than two inches the slight change inmixture resultingfrom the increased lift is not at all serious.

From the foregoing description taken in connection with thelaccompanying drawings it will be readily apparent to those. skilled inthe art that-the carburetor of this invention is far simpler and lessexpensive to produce than carburetors heretofore used on small portablesingle cylinder engines. It will also be clear that one of its chiefadvantages lies in the fact that it obviates the need for a float bowland float.

This advantage, of course, results from the suspension of the fuel tankdirectly beneath the fuel jet so that the fuel may be drawn by suctiondirectly up to the jet in such quantity as determined by the setting ofthe needle valve. Another advantage of this arrangement is that thesuction tube or pipe requires no check valve l 1. In a carburetor forinternal combustion engines: a hollow elongated body providing a mixturepassage opening to one end of the body, and an attaching flange on saidend of the b'ody having two sets of diametrically opposite bolt holesdisposed at ninety degrees to each other and through either of whichscrews may be passed for `securing the arm to an engine cylinder overthe mouth of its intake port, `oneyset of holes being `used for verticalenginesand the other for hori.

zontal engines, in either case the body being in the same position ofrotation about its longitudinal axis.

2. As an article of manufacture an elongated tubular body for acarburetor, adapted when in use,

to occupya horizontal position; said body comprising: a casting having abore providing a mixture Aus to rotatably mount a throttle valve; aflange at the bottom of the body and against which the top of a fueltank may be secured; a boss formed on named boss having a socket thereincommunicated -with the longitudinal bore through a restricted orifice,said socket being adapted to receive a needle valve, there being a boreextending down from the socket and communicating the socket interiorwith the exterior of the casting throughk the bottom thereof to receivea suction pipe; and an attaching flange on the body at the end of itsbore opposite the air inlet.

3. As an article of manufacture, a body for a carburetor, comprising:l acasting having a horizontal longitudinally extending mixture passage; anupstanding boss at one end of the body having an upwardly opening welltherein providing an air inlet to the mixture passage and having anupwardly facing seat for an air cleaner surrounding the mouth of thewell; another boss extending upwardly f rom the body intermediate theends thereof and having a substantially vertically disposed bore thereincommunicating with tank may be secured; the body having a socket thereinabove said flange and communicated with the mixture passage at one sidethereof, said socket being adapted to receive a fuel jet; the bodyhaving a bore extending down from the socket and through the bottom ofsaid flnage to receive va suction pipe; andan attaching flange on thebody at the end thereof opposite the air inlet.

4. An engine carburetor, comprising: a, body having a bore providing aninduction passage open at one end and having an air inlet into theinduction passage remote from its open end; means on the body formounting the same upon an engine cylinder with the open end oftheind-uction passage discharging into the intake port of the cylinder andwith the axis of the induction passage horizontal; a shallow fuel tank;a flange on the bottom of the body with its underside at an elevationclose to the bottom of the induction passage; means securing the top ofthe fuel tank to the underside of the flange with the induction passageaxially parallel with the normal level of fuel in the tank; the bodyhaving a substantially cylindrical fuel jet socket therein extendinglaterally from one side of the induction passage and at substantiallythe same elevation above the top of the tank as the induction passageand with its axis substantially horizontal, said socket havingrestricted communication at its inner end with the induction passagethrough an orifice opening to the induction passage at a point betweenthe air inlet and its open end; a suction pipe extending down from saidsocket through the flange and into thel fuel tank with its lower endnear the bottom .of the' tank;l a needle valve in said socket betweenitsconnection with the suction pipe and the orifice to control the lflowing motion about an axis normal to the axis of the induction passage andin a vertical plane which intersects the wall of the passage directlyadjacent to the point at which said orice opens to the inductionpassage.

HUGH S. BROWN. i WERNER E. ARMSTRONG. JOSEPH V. REICHENBACH.

REFERENCES CITED The following references are of record in the le ofthis patent:

Number 10 UNITED STATES PATENTS Name Date Raymond Sept. 3, 1912 'CravenDec. 25, 1 917 Irving Feb. 14, 1922 Buick Nov. 17, 1925 Pritchett May 3,1927 vBrandl et al. r Aug. 26, 1930 Rosner Aug. 11, 1931 Brandl et alSept. 8, 1931 Mikulasek Sept, 11, 1934 Bracke Oct. 22, 1935 Wirth et a1peo, 22, '1936 Wilson etal. Feb. 2, 1937 Irgens Feb. 21, 1939 EricsonMay 2, 1939 Smith Sept. 5, 1939 Adler July 29, 1941 Elleman Apr. 26,1949

